The present invention relates to improvements in fluidic oscillators and to a novel spray-forming output chamber for fluidic oscillators.
It has been recognized in the prior art that fluidic oscillators can serve not only as fluidic circuit components but also as fluid distribution or spray devices. (See U.S. Pat. Nos. 3,432,102; 3,507,275; 4,052,002). In all of these patents a fluid jet is caused to oscillate by means of fluid interaction using no moving parts, and the resulting oscillating jet is issued into the ambient environment to disburse the fluid therein. Other fluidic oscillators, such as described in U.S. Pat. No. 3,563,462, issue discrete pulses of fluid in alternation from two or more spray openings. In most applications for prior art fluidic oscillators it has been found that oscillator performance is dramatically affected by relatively small dimensional variations in the oscillator passages and chamber. It has also been found that prior art oscillators are extremely sensitive to properties of the sprayed fluid, such as viscosity, surface tension, temperature, etc.
Another concern with prior art oscillators, particularly when employed to achieve specific spray patterns, is that the desired spray patterns are not achieved immediately upon start up. Generally, the desired spray pattern is achieved only after the oscillator is substantially filled with the spray fluid; however, until the oscillator is filled it is quite common for a non-oscillating jet to issue from the device.
Prior art fluidic devices have been designed to operate in accordance with well established fluidic principles, such as Coanda effect, stream momentum exchange effects, and static pressure control effects. It is, in my opinion, this reliance upon these standard fluidic effects which brings about the aforementioned limitations and disadvantages.
It is an object of the present invention to provide a fluidic oscillator which operates on a different principle than previous fluidic oscillators and, thereby, is not shackled with the aforementioned disadvantages.
It is another object of the present invention to provide a fluidic oscillator which is relatively insensitive to dimensional manufacturing tolerances.
It is yet another object of the present invention to provide a fluidic oscillator having improved operating characteristics over large ranges of variations of operating fluid properties and thereby offer wider application capabilities than prior art fluidic oscillators.
An important aspect of fluidic oscillators, when utilized as spray or fluid dispersal devices, is the waveshape of the issued spray or dispersal pattern. Depending upon the desired distribution characteristics, the waveshape must be tailored accordingly. For example, as described in the aforementioned U.S. Pat. No. 4,052,002, relatively uniform spatial distribution of the fluid is achieved if the waveform is triangular with little or no dwell time at the extremes of the fan-shaped sweep. As more dwell time is introduced in the extremes of the sweep, spatial distribution becomes more dense at the extremes and less dense at the center. To achieve higher densities at the center, or between the center and extremes of the sweep is difficult. Moreover, to tailor the sweep pattern to achieve many desired spatial distributions is difficult in the prior art oscillators.
Further, droplet size, in the case of liquids sprayed from prior art fluidic oscillators, is an important consideration in two respects. First, specific droplet sizes are required for different spray applications. Second, certain droplet sizes have been found to be dangerous to inhale and must be avoided. In prior art fluidic oscillators, the size of the oscillator pretty much determines the range of droplet sizes in the issued spray pattern. Often it occurs that a particular oscillator size is necessary to achieve the desired droplet size, but that such oscillator size is impractical for that application because of space requirements.
Still another important characteristic of spray and dispersal patterns from fluidic oscillators is the sweep frequency. Again, this characteristic is determined by the oscillator size in prior art fluidic oscillators. An example of one frequency requirement would be in a massaging shower wherein the frequency should be such as to provide a massaging effect, or in an oral irrigator wherein a massaging effect is likewise desirable. On the other hand, when the oscillator is used as a nozzle for hair spray or anti-perspirant it is desirable that no massaging effect be felt. As described in the case of droplet sizes above, it often occurs that an oscillator size which is suitable for achieving the desired sweep frequency is not satisfactory for the space requirement of the overall device.
It is therefore an object of the present invention to provide an improvement for fluidic oscillators which permits control over the spray pattern, droplet distribution, droplet size and sweep frequency of issued fluid.
It is another object of the present invention to provide an output region, useful with any fluidic oscillator, which permits considerable variation in the spray pattern and characteristics of oscillators of specified sizes.
It is still another object of the present invention to provide an output region for a fluidic oscillator which employs an entirely novel principle of spray formation and thereby permits control of the angle, frequency, droplet size and distribution of the issued spray pattern.